A dual clutch of the type in question in the form of a clutch unit with two friction clutches is known from WO 2008/058508 A1. Here, a counterpressure plate is firmly connected for conjoint rotation to a crankshaft of an internal combustion engine by means of housing components. On both sides, the counterpressure plate forms friction surfaces for contact with friction linings of respective clutch disks connected for co-rotation with a transmission input shaft of a dual clutch transmission. Provided at an axial distance from said friction surfaces, on both sides, there is in each case one contact plate, which is arranged in such a way as to allow axial movement and prevent rotation relative to the counterpressure plate and is acted upon by a respective lever spring to give frictional engagement, said levers being supported on a housing component and being acted upon radially on the inside along an axial actuating path by respective actuating systems. Here, the two lever springs are arranged axially adjacent to one another, and the movement of the contact plate arranged on the side of the counterpressure plate facing the internal combustion engine is accomplished by means of a tie rod, which engages on the contact plate over the counterpressure plate or through the latter and moves the contact plate when acted upon axially by the lever spring.
In this case, the two friction clutches are designed as “press-shut” or “pull-shut” friction clutches (normally open). This means that, when the radially inner lever tips of the lever springs are pushed in the direction of the internal combustion engine, the respective friction clutch is transferred from the open state to the closed state by the contact plates bringing the respective friction linings into frictional engagement with the counterpressure plate.
In this case, one friction clutch is opened and the other friction clutch is closed when the motor vehicle is being driven, and hence torque is transmitted to the driven wheels via the component drive train of the dual clutch transmission which is associated with the closed friction clutch, and the motor vehicle is driven, when a gear is engaged. In the component drive train which is associated with the open friction clutch, a corresponding subsequent gear can be preselected, and thus a gear change is performed in the form of an overlapping shift by swapping the torque provided by the internal combustion engine to the other friction clutch and hence to the other component drive train, with both friction clutches transmitting some of the torque in a transitional phase to avoid an interruption in tractive effort.
In the friction clutch disclosed, an overlapping shift is accomplished by a procedure in which one actuating system performs an actuating path in the direction of the internal combustion engine, thereby closing the friction clutch concerned, while the other actuating system traverses an actuating path in the direction of the dual clutch transmission in order to open this friction clutch. In order to make such overlapping shifts possible at all, the axial movements of the lever springs which take place during this process must be kinematically disentangled. For this purpose, the lever springs are spaced apart axially from each other, thereby additionally increasing the axial installation space requirement, which is already very large in the case of dual clutches.
It is therefore the object of the invention to propose a dual clutch with a smaller axial installation space requirement which simultaneously offers the possibility of overlapping shifts.